Photographic vesicular materials and imaging process therefor

ABSTRACT

VISICULAR PHOTOGRAPHIC MATERIALS COMPRISING A POLYMERIC VEHICLE AND A LIGHT DECOMPOSABLE AGENT. THE POLYMERIC MATERIAL IS A MIXTURE OF A RESIN A AND A RESIN B. BY ADJUSTING THE RELATIVE PROPORTIONS OF THESE RESINS, THE PHOTOGRAPHIC GAMMA OF THE FILM CAN BE ALTERED. THE RESIN A IS AN ESTER OR ACETAL OF POLYVINYL ALCOHOL. THE RESIN B IS AN EPOXY RESIN, A PHENOL FORMALDEHYDE RESIN, A UREA-FORMALDEHYDE RESIN, A MELAMINE-FORMALDEHYDE RESIN, A CELLULOSE ESTER, A SILICONE RESIN, AN ISOCYANAE RESIN OR A COPOLYMER OF MALEIC ANHYDRIDE WITH STYRENE. PREFERABLY, THE AMOUT OF RESIN A IS AT LEAST 50% AND THE AMOUNT OF RESIN B IS UP TO 50%.

United States Patent Oihce 3,552,965 Patented Jan. 5, 1971 US. CI. 9648 11 Claims ABSTRACT OF THE DISCLOSURE Vesicular photographic materials comprising a polymeric vehicle and a light decomposable agent. The polymeric material is a mixture of a resin A and a resin B. by adjusting the relative proportions of these resins, the photographic gamma of the film can be altered. The resin A is an ester or acetal of polyvinyl alcohol. The resin B is an epoxy resin, a phenol formaldehyde resin, a urea-formaldehyde resin, a melamine-formaldehyde resin, a cellulose ester, a silicone resin, an isocyanate resin or a copolymer of maleic anhydride with styrene. Preferably, the amount of resin A is at least 50% and the amount of resin B is up to 50%.

This is a division of prior U.S. application Ser. No. 768,943, filed Aug. 12, 1968, now U.S. Pat No. 3,498,786 which in turn is a continuation of application Ser. No. 403,633, filed Oct. 13, 1964, now abandoned.

The present invention relates to photography and, more particularly, to the production of vesicular images.

Vesicular images are formed in photographic film by small bubbles or vesicles of gas which are formed and trapped in the areas of the film exposed to light and which refract light. Generally speaking, the film has a colloid or a resin coating or vehicle on a backing material and a light-sensitive agent or sensitizer, most commonly a diazo compound, dispersed throughout the coating. When the film is exposed to light, the sensitizer releases molecules of a gas-nitrogen in the case of diazo compounds. These ordinarily do not form vesicles immediately, but they do so when the film is heated, presumably because the vehicle is relaxed suificiently on heating for the gas molecules to diffuse together into bubbles and for the bubbles to expand. The resulting vesicles make the vehicle opaque to transmission of light in the exposed areas and also reflect and scatter light so that they appear white.

Vesicular photographic materials have been of only limited use in certain applications because of lack of flexibility in the gray scale, or photographic gamma, they possessed. That is, in general it is desirable to reduce the contrast or gamma of light-scattering photographic materials, while in other cases it may be desirable to increase the gamma. It has been known to reduce the photographic gamma while reducing the maximum obtainable density. However, the resultant loss of density range limits the usefulness of this technique.

It is also known to reduce the photographic gamma by treating a vesicular photographic material in a heated aqueous fluid, as is more fully described in US. Pat. 3,149,971. This procedure gives good results. However, there is a need for other techniques which avoid the additional process step required.

It is an object of the present invention to provide, in an improved vesicular photographic film, means for adjusting the photographic gamma of the film in which the vehicle is comprised of a blend of two resins to be designated further herein as resin A and resin B. Resin A is a polymer containing an ester or acetal derivative of polyvinyl alcohol; resin B is taken from the group consisting of epoxy resins, phenol formaldehyde resins, urea formaldehyde resins, melamine-formaldehyde resins, cellulose esters, such as cellulose acetate butyrate and cellulose acetate and cellulose nitrate, silicone resins, isocyanate resins, and copolymers of styrene and maleic anhydride.

The ester derivatives are generally obtained by polym erization of esters of vinyl alcohol with aliphatic or aromatic carboxylic acids. The aliphatic acids are preferred, the most suitable being lower fatty and unsaturated acids containing up to about six carbon atoms, such as acetic acid, propionic acid, valeric acid, vinyl acetic acid or crotonic acid. However, higher fatty acids such as octanoic may be used, particularly in combination with lower fatty acids. Suitable aromatic acids include benzoic acid, naphthoic acids and phenyl acetic acid. The ester polymers may be obtained from the monomer by any conventional polymerization method, i.e., bulk, solution or aqueous emulsion or dispersion, in the presence of, e.g. a free radical or ionic catalyst, the details of which form no part of the present invention.

Polyvinyl acetals are generally made by reaction between aldehydes and polyvinyl alcohol or polyvinyl esters such as polyvinyl acetates. It is preferred that saturated lower aliphatic aldehydes be employed containing up to six carbon atoms, particularly butyraldehyde and formaldehyde. However, small amounts of higher aliphatic aldehydes or aromatic aldehydes such as benzaldehyde may be included. The polyvinyl acetal polymers may contain small amounts of residual hydroxyl groups which have not been converted to the acetal derivative or of acetate groups which have not been converted to hydroxyl. However, no more than about 60% of the hydroxyl groups, and preferably no more than 25% should remain as free hydroxyl groups, i.e., not converted to a derivative thereof.

It will be appreciated that while the above description of preferred polymers has been directed to homopolymers, copolymers containing more than one acetal, or ester group may be used. Thus polyvinyl acetals may contain two or more types of acetal groups or, e.g., acetate units as well as acetal. In addition, relatively minor amounts of ethylenically unsaturated monomers containing one or more C=C groups may be copolymerized, e.g., up to about 5%, as long as the character istics of the polymer are essentially not altered so as to render it unsuitable.

Epoxy resins which may be used preferably are glycidyl ethers of polyhydric phenols derived by reaction of a polyhydric phenol with epichlorohydrin. For example,

one may use the glycidyl ethers of his phenol A having the formula where n is a number up to about 10-15. In place of his phenol A, other suitable epoxy resins may be based upon mononuclear diand trihydroxy phenols and other polynuclear polyhydroxy phenols, such as resorcinol, hydroquinone, pryrocatechol, phloroglucinol, bis phenol F, 2,4, 4'-trihydroxydiphenyl dimethyl mehane, 4,4'-dihydroxy 'biphenyl, and the like. In addition, one may use epoxidized unsaturated oils, as described more fully in the Encyclopedia of Chemical Technology, Second Supplement Volume (1960) and other epoxide group-containing materials. However, the glycidyl ethers of bis phenol A are preferred and are readily available commercially.

Phenolic, urea or melamine resins which are used are condensates of a phenol, e.g., phenol and p-alkyl phenols, melamine or urea with formaldehyde. A wide variety of these materials are known and commercially available. For example, detailed descriptions may be found in the Encyclopedia of Chemical Technology, volume 1 (1947) pages 741-769, and volume (1953) pages 335-368.

The styrene maleic anhydride copolymers may be prepared by any copolymerization system known for these monomers, e.g., bulk, solution or emulsion polymerization in the presence of a catalyst. Lower molecular weight materials are desirable from the standpoint of compati- 'bility and solubility, but higher molecular weight resins also may be used.

The isocyanate resins are isocyanate-ended prepolymers derived by reaction of an excess of polyisocyanate such as tolylene diisocyanate or p,p'-diisocyanatodiphenylmethane with a polyester, polyether or a polyesteramide. Such materials normally are used with additional amounts of polyester, polyether or polyesteramide, and with or without water, in the making of polyurethanes. They are described in prior U.S. patents and in Polyurethanes, Chemistry and Technology by Saunders and Frisch and Polyurethanes by Bernard A. Dombrow.

The silicone resins, as are known, are polymers in which the repeating units have the formula In which R may be alkyl, preferably lower alkyl, e.g., methyl or ethyl, aryl, e.g., phenyl, tolyl, xylyl or naphthyl, aralkyl, e.g., benzyl, alkenyl, e.g., vinyl or allyl, or cycloalkyl, e.g., cyclohexyl. Other groups which may be attached to the silicon atom are hydrogen, ONa, OK, or --OR Where R has the same meaning as above. As will be appreciated, depending on the value of n in the above formula, the silicone may be linear, branched or cross-linked. F or the most part, silicones which are linear or slightly branched but not extensively cross-linked are prefered because these tend to be more soluble in the organic solvents used in making films. Suitable examples are p'olysiloxanes, having repeating units of the general formula with end groups such as where R is methyl, ethyl, propyl or vinyl. Detailed descriptions of such polymers may be found, for example, in The Encyclopedia of Chemical Technology, vol. 12, page 393 and An Introduction to the Chemistry of the Silicones by E. G. Rochow, 2d ed, 1951.

The resins A and B are suitably blended by dissolving in a mutual solvent or by dissolving them in separate solvents and mixing the solutions together. The resulting resin solution is mixed with the sensitizer, preferable first dissolved in a separate solution, and the resulting mixed solution is coated on a substrate and dried, for example, by heating in an oven at 240 F. It will be observed that some of the resins B may be capable of reacting with acetate, hydroxy or acetal groups of resin A. Consequently, a certain amount of cross-linking may take place, e.g., during this drying step.

After the film is thus prepared, there are at least three dilferent methods of processing it. In one form, the film is exposed to image-forming light, e.g., by being placed in contact with a transparency and exposed to light passing through the transparency. Then, the film is heated to 160300 F. for to 3 seconds. This will produce an image of the opposite photographic sign from the transparency. Thus if the transparency is a negative, a positive vesicular photograph will result.

A second processing system which can be used is first described in U.S. Pat. 2,911,299. In it, the film is exposed to image-forming light and gas released by the sensitizer is allowed to diffuse from the vehicle at a temperature too low for development to take place. Then the film is exposed overall to uniform light, which activates undecomposed sensitizer, and is heated to cause development at 160300 F. for A to 3 seconds, either during or shortly after the second exposure, but before the gas has substantially diffused from the film. This results in image formation in areas not originally struck by light and an image of the same photographic sign as the transparency. Thus a negative transparency results in formation of a negative vesicular photograph which might be called a reversal image or direct image.

The third processing system is that described in U.S. Pat. 3,457,071. In that system, the film is exposed to image forming light of relatively low intensity for at least about 0.5 second and preferably forat least about 2.0 seconds. That is, the light is of low enough intensity that the film does not receive a normal exposure in less than 0.5 second and preferably 2.0 seconds. Then the film receives an overall exposure of light intensity which is sufficient to expose the film in less than 0.2 second and preferably less than 0.01 second. Overexposure or longer exposure can be tolerated, but there must be sufficient light to properly expose the film during the indicated time. This procedure avoids a separate diffusion step as used in the method of U.S. Pat. 2,911,299. In some cases, no heating is required to cause development, and the image appears spontaneously. However, in other cases, some heating may be used to advantage, as more fully de scribed in U.S. Pat. 3,457,071.

Any suitable substrate may be employed for the photographic materials. For films, the prefered materials are films of Mylar (polyethylene terephthalate), polyethylene and polypropylene. Paper backings, metal plates and glass slides also are useful for certain applications. Thus, while films are refered to herein, it will be understood that the inventin embraces any backing layer.

It has been found that by mixing resins A and B in different proportions it is possible to adjust the photographic gamma of the films and frequently to increase the photographic density. As the amount of the resin B is increased, the degree of change of photographic gamma will generally increase accordingly. The exact proportions used will, of course, vary according to the desired result. For any given pair of resins, it is possible to determine the effect of changes in proportions by making films from them and determining the value of gamma by conventional sensitometry. A graph is then made in which gamma is plotted as a function of composition, which permits selecting the exact composition for any desired value of gamma. However, in general, the amounts of the resins will fall within the ranges to 50% resin A and O to 50% resin B. It also has been found that alterations in the relative amounts of resins A and B change the photographic speed and projection density of the film. In general film speed increases when the contrast is reduced, in a manner somewhat analogous to commercially available silver halide films.

The following examples illustrate the practice of the invention, all parts being by weight.

EXAMPLE I The following constituents were combined with stirring to form a solution:

Parts Butyraldehyde polyvinyl acetal (80% acetal, 2.5%

acetate, 17.52l.0% hydroxyl) 25 General Electric Methylon 75-108 1,4 dioxane 200 p-Diazo N,N-dimethyl aniline zinc chloride salt 4 Acetonitrile 80 Methylon 75-l08 has the formula ?CH2CH=CH2 H(3n) (CH2OH)n where n: l-3.

The solution was applied to a backing layer of Mylar film and dried. Then the film was exposed to light from a 500 watt tungsten filament incandescent lamp spaced about 3 inches from the film through an image bearing transparency for twenty seconds and developed by heating for two seconds at 240 F.

An image was obtained which showed a maximum projection density of 2.74.

EXAMPLE II The following constituents were carefully mixed in an open vessel with stirring continued until a uniform solution obtained.

Parts Formaldehyde polyvinyl acetal (50% acetal, 4050% acetate, 5.0-6.5% hydroxyl) 25 SMA 4000A 1 5 1,4-dioxane 100 p-Diazo N,N-dimethyl aniline zinc chloride salt 4 Acetonitrile 80 A eopolymer of styrene and maleic anhydride which is a dry powder, has a. molecular weight of 700, a melting range of 50-70 C., an acid number of 415, a specific viscosity at 30 C. gms., 100 m1. acetone) of 0.53. a bulk density of 37.9 lbs/ft. and a true density of 76.4 1hs./ft.

The resultant solution was coated on a glass plate which was dried, exposed to light through an image bearing transparency and developed as in Example I. The image showed a maximum projection density of 2.68.

EXAMPLE III Example II was repeated using as the constituents of the solution:

Parts Butyraldehyde polyvinyl acetal (88% acetal, 02.5%

acetate, 913.0% hydroxyl) 25 Resimene 881 1 5 A melamine formaldehyde resin composition Type III, 60i2% solids with butanol and 20% xylol having an acid number less than 1 (mg. KOH to neutralize 1 g. resin solids) and a. viscosity L-P (Gardner-Holt bubble tube standard at C.).

The image showed a maximum projection density of 2.76.

EXAMPLE IV Example II was repeated, using as the constituents of the solution:

15 Parts Formoldehyde polyvinyl acetal (82% acetal, 9.5-

13.0% acetate, 5.06.5% hydroxyl) 25 SR-82 1 5 1,4-dioxane 100 20 p-Diazo N,N'dimethyl aniline zinc chloride salt 4 Acetonitrile 80 1 A silicone resin available as an uncatalyzed, light strawcolored solution in Xylol containing 60I 1% solids, having a specific gravity of 1.06 and a viscosity of 5-30 cps. (Gardner- 5 Holt).

The image obtained showed a maximum projection density of 2.58.

EXAMPLE V The following materials were combined in 80 parts of acetonitrile to form a solution:

Parts Butyraldehyde polyvinyl acetal (80% acetal, 02.5%

acetate, 18.020% hydroxyl) 25 Mondur S 5 1,4-dioxane 180 p-Diazo N,N-dimethyl aniline zinc chloride salt 4 Mondur S is a light-colored, stabilized polyisocyanate adduct known for use with polyester resins in the formulation of bake-type one-component room temperature-stable urethane coatings. It has a specific gravity of 1.26-1.28, a total solids content of about 95%, available NCO, 11.5- 13.5% and a softening point of l20 C.

The resultant solution was coated on a thin film of Mylar and dried in an oven at 240 F. for 5 minutes. The dried film was placed in contact with a microfilm transparency and exposed to light through the transparency from a mercury arc lamp (General Electric Hl00A4 IT) spaced 2 inches away for 20 seconds. The film was then developed by heating to 240 F. for two seconds.

An image was obtained which showed a maximum projection density of 2.47.

In the following examples, solutions were prepared from the constituents indicated and films were made as described in Example I. Then the films were exposed and developed as also described in Example I.

EXAMPLE VI Parts Butyraldehyde polyvinyl acetal (80% acetal, 0-1.0%

acetate, 18.020.0% hydroxyl) 25 Araldite 6097 1 5 1,4-dioxane 250 p-Diazo N,N-dimethyl aniline zinc chloride salt 4 Acetonitrile 80 1 A bis phenol A-epichlorohydrin condensate by Ciba having a. melting point of 130, an epoxide equivalent of 1,785 and a viscosity at 25 C. (Gardner-Holt) of Z.1.

The image obtained showed a maximum projection density of 3.00.

7 EXAMPLE v11 Parts Formaldehyde polyvinyl acetal (82% acetal, 9.5-

13.0% acetate, 5.06.0% hydroxyl) 25 Uformite F-240 1 5 1,4-dioxane 120 p-Diazo N,N-dimethyl aniline zinc chloride salt 4 Acetonitrile 80 A urea-formaldehyde resin available in clear, colorless form as 601270 solids in the xylol-"butanol ('1 :1 having an acid number solids basis 38, specific gravity 1.02, pounds per gallon 8.5, viscosity (Gardner-Holt at 25 C.) L-Q, mineral thinner tolerance 50 min.

The image obtained had a maximum projection density of 2.75.

EXAMPLE VIII Parts Formaldehyde polyvinyl acetal (70% acetal, 22-30% acetate, 5.57.0% hydroxyl 20 Cellulose acetate butyrate 6 1,4-dioxane 200 p-Diazo N,N-dimethyl aniline zinc chloride salt 4 Acetonitrile 40 The image obtained showed a maximum projection density of 2.34.

EXAMPLE IX Parts Butyraldehyde polyvinyl acetal (80% acetal, -2.5%

acetate, 17.52l.0% hydroxyl) 25 Nitrocellulose (RS) 3 1,4-dioxane 200 Methyl ethyl ketone 20 p-Diazo N,N-dimethyl aniline 4 Acetonitrile 40 The image obtained showed a maximum projection density of 2.74.

Ethyl cellulose can be used in place of nitrocellulose in the above formulation.

EXAMPLE X To illustrate the eifect of varying amounts of resins A and B, three films were made according to the method of Examples VI-IX using the following:

( 1 Parts Polyvinyl formal 100 Dioxane 480 Dimethyl amino benzene diazonium chloride, boron Acetonitrile 320 Epon 1001 is an epichlorohydrin bis phenol A type epoxy resin having a melting point of 6476 C. an epoxide equivalent of 450-525, an average molecular weight of 900-1000 and a viscosity of 25 C. (Gardner-Holt) C-G.

Samples of the respective films were exposed on a sensitometer and developed at 240 F. to make a copy of the step wedge of reversed photographic sign. The following results were obtained.

(1) projection density (f/ 5 apertures) of 2.0 (2) projection density (f/S aperture) of 2.46 (3) projection density (f/S aperture) of 2.7

The photographic contrast (gamma) decreased and the photographic speed increased progressively from samples 1 through 3.

EXAMPLE XI The following formulation was used following the method of Example I:

. Parts Gelva (M-7, VlOOR) (polyvinyl acetate copolymer) 25 Methyl ethyl ketone Distilled water 5 General Electric Methylon 75-108 5 p-Diazo N,N-dimethyl aniline zinc chloride salt 4 Acetonitrile 40 The following three formulations were used in making and using films, following the method of Example I:

EXAMPLE XII Parts Gelva V-60 25 Epon 1001 5 Methyl ethyl ketone p-Diazo N,N-dimethyl aniline Zinc chloride salt 4 Acetonitrile 40 Gelva V-60 is a homopolymer of vinyl acetate supplied in the form of granules whose viscosity is 54-66 cps. in benzene solution containing 86 grams of resin per 1000 ml. of solution, determined at 20 C. with an Ostwald-Cannon-Fenske viscometer, molecular Weight (wt. av.) is 300,000, softening point is 385 F. (determined by a modified Kraemer and Sarnow method using 10 grams of mercury over a 6.35 mm. cylindrical plug of Gelva Resin in a 7 mm. diameter glass tube), heat seal temperature is -195 F. (the minimum temperature required for heat sealing of a 1--1.5 mil (dry) film cast from methanol solution on ditto paper dried at room temperature for 45 minutes, then force dried for one hour at 70 C. conditioned for 16 hours at 73 F., 50 percent R.H., using a PACK-RITE 1.5 sec. dwell, 10 psi. pressure, on 4" x sample, face to face), maximum tensile strength is 6500 p.s.i. (molded specimens2%" gauge x A" x 0.0 "-conditioned 48 hours at 73 F., 50% RH. Instron Tester at 2 in./min. crosshead speed) percent elongation at yield is 4.8, abrasion resistance is 59 mg. weight loss (Taber abrasion in mg. loss/1000 revs. on cast film conditioned 48 hours at 73 F., 50% RH, C-lO wheels-1000 gm. load), and second order transition temperature is 27 C.

EXAMPLE XIII Parts Gelva V100 25 General Electric Methylon 75-108 5 Methyl ethyl ketone 100 p-Diazo N,N-dimethyl aniline zinc chloride salt 4 Acetonitrile 40 Gelva V100 is a homopolymer of vinyl acetate supplied in the form of granules whose properties, determined by the method stated for Gelva V60 are as follows: viscosity, 99-110 cps.; molecular weight, 500,000; softening point, 446 F.; maximum tensile strength, 7200 p.s.i.; percent elongation at yield, 4.6; abrasion resistonce, 64 mg. weight loss; second order transition temperature, 28 C.

EXAMPLE XIV Parts Gelva V-800 25 Uformite F-240 5 9 EXAMPLE XIV-Continued Parts Methyl ethyl ketone 100 p-Diazo N,N-dimethyl aniline zinc chloride salt 4 Acetonitrile 40 Gelva V-800 is a homopolymer of vinyl acetate supplied in the form of granultes whose properties, determined by the methods stated in Example XII for Gelva V-60 are as follows: viscosity, 700-1000 cps.; molecular weight, about l.5 heat seal temperature, 205-2l5 F.; maximum tensile strength, 7300 p.s.i. percent elongation at yield, 4.3; abrasion resistance, 59 mg. weight loss; second order transition temperature 29 C.

As can be seen from the foregoing, the vesicular photographic films described herein provide a useful means for controlling sensitivity and the value of gamma. In addition, in the images obtained, the bubbles can be made very small, thereby improving resolution and the bubbles have unusually high stability. Thus it can be seen that these films have many important advantages and achieve the objectives of the invention.

The invention has now been described with respect to preferred embodiments, but it will be appreciated that various changes may be made in the materials used and the details of the processes, and that no limitation thereto is intended, except as the invention is defined in the appended claims. Thus, for example, while particular sensitizers are described in the foregoing examples, any light decomposable solid agent of the type known in vesicular photography may be used, if it is of the type which, upon exposure to light, decomposes into products which are volatile upon warming to form the above-described radiation-scattering discontinuities. The preferred sensitizers are non-reactive to the vehicle and, upon exposure to light, decompose into products which are chemically non-reaction to said vehicle and which are to form radiation scattering discontinuities only in the light struck areas in said vehicle to thereby furnish a record. Of the preferred sensitizers, those which are especially useful on exposure to light, particularly the diazonium salts. Full descriptions of these sensitizers may be found, for example, in US. Pat. 3,457,071, and the prior patents referred to therein, any of the sensitizers disclosed in said patent being usable herein.

Similarly other changes may be made in the process such as the kind of light source used, the conditions of development, and the like, within the scope of the invention, since the examples herein are provided only for the purpose of illustration.

What is claimed is:

1. A photographic material capable of furnishing a record solely in the form of a distribution pattern of radiation-scattering discontinuities formed within an otherwise substantially homogeneous vehicle, said material being in the form of a dry, water-resistant film, the continuous phase of said film being essentially a synthetic, water-insoluble, non-Water swelling mixture of a resin A and a resin B, said mixture containing at least 50% by weight of resin A, said resin A being a polyvinyl alcohol in which at least 40% of the hydroxyl groups are in the form of a member of the group consisting of acetals with aldehydes containing up to about six carbon atoms and esters with an organic carboxylic acid selected from the class consisting of aliphatic carboxylic acids containing up to about six carbon atoms, mixtures thereof with higher aliphatic carboxylic acids, benzoic acid, naphthoic acid and phenyl acetic acid, and said resin B being a copolymer of maleic anhydride with styrene, and a light decomposable solid agent substantially uniformly dispersed therein as the sole essential decomposable agent, said decomposable agent itself being non-reactive to said vehicle and upon exposure to light decomposing into products which are chemically non-reactive to said vehicle and which are capable upon warming of forming said radiation-scattering discontinuities only in the light struck areas in said vehicle to thereby furnish said record.

2. A photographic material as set forth in claim 1 in which the amount of said resin A is less than but at least 50% by weight of the total weight of resin A and resin B and the amount of said resin B is up to 50% by weight of said total weight.

3. A photographic material as set forth in claim 1 in which said resin A is butyraldehyde polyvinyl acetal. 4. A photographic material as set forth in claim 1 in which said resin A is formaldehyde polyvinyl acetal.

5. A photographic material as set forth in claim 1 in which said resin A is a polyvinyl ester which is an ester of polyvinyl alcohol with an organic carboxylic acid.

6. A method of producing a vesicular image which comprises,

exposing to image forming light a vesicular photographic material capable of furnishing a record solely in the form of a distribution pattern of radiationscattering discontinuities formed within an otherwise substantially homogeneous vehicle, said material being in the form of a dry, water-resistant, nonwater swelling film, the continuous phase of said film being essentially a synthetic, water-insoluble, non-hygroscopic, non-water swelling mixture of a resin A and a resin B, said mixture containing at least 50% by weight of resin A, said resin A being a polyvinyl alcohol in which at least 40% of the hydroxyl groups are in the form of a member of the group consisting of acetals with aldehydes containing up to about six carbon atoms and esters With an organic carboxylic acid selected from the class consisting of aliphatic carboxylic acids containing up to about six carbon atoms, mixtures thereof with higher aliphatic carboxylic acids, benzoic acid, naphthoic acid and phenyl acetic acid and said resin B being a copolymer of maleic anhydride with styrene, and a light decomposable solid agent substantially uniformly dispersed therein as the sole essential decomposable agent, said decomposable agent itself being non-reactive to said vehicle and upon exposure to light decomposing into products which are chemically non-reactive to said vehicle and which are capable upon warming of forming said radiationscattering discontinuities only in the light struck areas to thereby furnish said record, and

thereafter heating said photographic material to cause development.

7. A method as set forth in claim 6 in which the amount of said resin A is less than 100% but at least 50% by weight of the total weight of resin A and resin B and the amount of said resin B is up to 50% by weight of said total weight.

8. A method as set forth in claim 6 in which said resin A is formaldehyde polyvinyl acetal.

9. A method as set forth in claim 6 in which said resin A is butyraldehyde polyvinyl acetal.

10. A method as set forth in claim 6 in which said resin A is a polyvinyl ester which is an ester of polyvinyl alcohol with an organic carboxylic acid.

11. A method of producing a vesicular image which comprises,

exposing to image forming light a vesicular photographic material capable of furnishing a record solely in the form of a distribution pattern of radiationscattering discontinuities formed within an otherwise substantially homogeneous vehicle, said material being in the form of a dry, water-resistant, non-water swelling film, the continuous phase of said film being essentially a synthetic, water-insoluble, non-hygroscopic, non-water swelling mixture of a resin A and a resin B, said mixture containing at least 50% by weight of resin A, said resin A being a polyvinyl alcohol in which at least 40% of the hydroxyl groups 12 are in the form of a member of the group consisting heating said photographic material to cause developof acetals with aldehydes containing up to about ment and the formation of a vesicular image. six carbon atoms and esters with an organic carboxylic acid selected from the class consisting of References Cited aliphatic carboxylic acids containing up to about six 5 UNITED STATES A N S carbon atoms, mixtures thereof with higher aliphatic carboxylic acids, benzoic acid, naphthoic acid and i g g i g phenyl acetic acid and said resin B being a copolymer 2980534 4/1961 Printy et a1 "5 of maleic anhydride with styrene, and a light de- 41 4 5/1962 James et composable solid agent substantially uniformly dis- 1O 3143418 8/1964 Priest et persed therein as the sole essential decomposable 3244523 4/1966 Growald i 96 9lX agent, said decomposab e agent itself being non-reactive to said vehicle and upon exposure to light de- 3402044 9/1968 Stemhofl et 96-91 composing into products which are chemically non- FOREIGN PATENTS reactive to said vehicle and which are capable upon 15 5 5 10/1960 Great Britain 96 91 Warming of forming said radiation-scattering discontinuities only in the light struck areas to thereby fur- NORMAN G. TORCHIN, Primary Examiner nish said record, diffusing said volatile products from said vehicle with- BOWERS ASsStantEXamm out forming an image therein, 20 U S Cl X R subjecting said vehicle to substantially uniform irradiation to cause decomposition of an additional quan- 115 tity of said decomposable agent, and

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 552,965 Dated Jan. 5, 1971 Inventor) Norman T. Notley, et a] It is certified that error appears in the above-identified paten1 and that said Letters Patent are hereby corrected as shown below:

Delete from the heading in Column 1 the words:

"assignors to Kalvar Corporation, New Orleans,

La. a corporation of Louisiana" Signed and sealed this 20th day of June 1972.

(SEAL) Atte st:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents 

